Magnetic alloy



Patented May 1, 1928.

UNITED STA WILLOUGHIBY STATHAM SUITE, NEWTON POIEPLEFORD, HENRY JOSEPH GABNETT,

TES QPYAT'ENT, OFFICE.

or SEVENOAKS, AND JOHN ANGEL HOLDEN, or emna'ranx, ENGLAND.

maennrrc ALLOY.

No Drawing. Application filed January 21, 1927, Serial No. 162,674, and in Great Britain September 8,

This invention relates to magnetic alloys which have high electrical resistance.

According to this invention alloys are composed ofr-- 6 Per cent. Iron 10 -17 Silicon 1.5- 4: A fourth element 1 4:

and the'balance nickel,

the fourth element may be, for example, chromium, tungsten, vanadium, or molybdenum.

Preferably however, alloys com.prise:

1 I Per cent. Iron 12. 5-13. 5 Silicon; 1. 5- 2. 0 A fourth element 2. 0- 2.5

Alloys in accordance with this invention should contain practically no carbon, but additions of one or more suitable deoxidizing metals, such as manganese, magnesium, cadmium, or the like, may be made.

Such alloys are characterized by their very high magnetic permeabilities with very feeble magnetizing forces, by their very low. hysteresis, and by their high electrical resistance. Y

For example, an alloy containing:- I

. Percent.

Nickel 82 Iron 14 Silicon 2 Chromium -2 and a trace of manganese,

after forging, drawing to a fine wire and annealing, had the high electrical resistance of 4 57.7 microhms per cm., and-the following magnetic properties a W ith H=.001 gagss 6500 and the balance nickel, 5 was forged from the reduced by wire drawin operations to wire 30 S. W. G. and finally eat treated by the process described below. It then exhibited the following magnetic and electrical properties.

Magnetic permeability at H= .O01=10,000 .01 =.1 0,300 H= .05 ='10,550 H= .10 .=13,100 f H= .20 =22,500

H=1.00 6,000 Its electrical resistance was 58 microhms per cm.

- The heat treatment consisted of heating the wire rapidl to 880 C. in an inert (nitrogen) atmosp iere, allowing it to remain at that temperature for two minutes, and finally cooling rapidly by withdrawing it from the furnace into the air.

If the heat treatment is prolonged, the magnetic properties are inferior; further,

slow cooling is also detrimental. Thus they optimum cooling speed is governed by the size of the articles; objects, such as coils, with a thickness of require quenching. Telegraph signalling conductors, loaded with wire, or tape, made from the above alloys, can be successfully heat treated by with-. drawing through the furnace, and then through a. water jacketed tube. For the heat treatment of the shore-ends ofa submarine signalling conductor, where the hysteresis losses must be reduced to a minimum, a

rather lower temperature is preferable, andwe have found that 850860 C. is the best, and instead of a water jacketed tube, it is preferable to draw .the conductor into a chamber provided with a suitable moving current of inert gas, such as nitrogen. The

speed of the loaded conductor is governed by its size'and controlled by the velocity of its forward travel. In practice, itis found that I two minutes at the prescribed temperature is the correct period, thus the velocity of travel can be ascertained by experiment with two or three loaded conductors of different weights, from which the time taken to reach.

the temperature of the furnace can be ascertained, and when this factor is known the velocity of the moving loaded conductor can be deduced.

In order to secure the exceedingly hi h initial permeability of 10,000 very care 111. metallurgical practice is essential. Pure raw materials are necessary, and a melting process, in which noncontamination takes place,

is also an essential. The ratio between the four elements governs the properties of the alloys. Ifthe iron content is increased the magnetic permeability will be reduced, unless either the silicon and the fourth element (such as chromium) or both, are reduced. If, for example, the above alloy, with an initial permeability of 10,000, contained 16.00% of iron, with a reduction'in nickel corresponding to this increase in iron, and the other elements in the same percentage,

the initial permeability would be only 4,000.

It follows that if either the silicon or the fourth element (such as chromium) is increased for the purpose of raising the electrical resistance, to maintain high initial permeability a reduction in the iron content is necessary.

There is, however, a limit to which this may be carried out, an alloy containing Per cent.

Iron 1 10.5

Silicon 2.2

'' Chromium 2.7

Nickel, the balance,

Per can t. Iron 16.9 Chromium 2.2 Silicon 1.7

Nickel, the balance.

lVit-h H=.001 gauss [.L 30l0 The electrical resistance of this alloy is 60.3 microhms per cm What we claim is 1. Magnetic substantially carbon free ma.- terial comprising iron 10 to 17%, silicon 1.5 to 4%,- a fourth metal selected from the group comprising chromium, tungsten, vanadium, and molybdenum 1 to 4% and the balance nickel.

2. Magnetic substantially carbon free maeemae tcrial comprising iron 12.5 to 13.5%, silicon 1.5 to 2%, a fourth metal selected from the group comprising chromium, tungsten, vanadium, and molybdenum 2 to 2.5% and the balance nickel.

3. Magnetic substantially carbon free material comprising iron 10 to 17%, silicon 1.5

to 4%, vanadium 1 to 4% and the balance nickel.

4. Magnetic substantially carbon free material comprising iron 12.5 to 13%, silicon 1.5 to 2%, vanadium 2 to 2.5% and the bal-' ance nickel.

5. Magnetic substantially carbon free material comprising iron 10 to 17%, silicon 1.5 to 4%, a fourth meta-l selected from the group comprising chromium, tungsten, vanadium, and molybdenum 1 to 4%, a small percentage of a deoxidizing metal, and the balance small percentage of a 'deoxidizing metaland the balance nickel.

7. Magnetic substantially carbon free material comprising iron 10 to 17%, silicon 1.5 to 4%, vanadium 1 to 4%, a small percentage of a deoxidizing metal, and the balance nickel. I 8. Magnetic substantially carbon free material comprising nickel 82%, iron 14%, silicon 2%, a met-a1 selected from the group comprising chromium, tungsten, vanadium, and molybdenum 2% and a trace of manganese;

9. Magnetic substantially carbon free material comprising iron 12.90%, silicon 1.60%, a metal selected from the group comprising chromium, tungsten, vanadium, and molybdenum 2.20%, manganese 0.30% and the balance nickel.

10. Magnetic substantially carbon free material comprising iron 10.5%, silicon 2.2". a metal selected from the group comprising chromium, tungsten, vanadium, and

molybdenum 2.7% and the balance nickel.

11. vMagnetic substantially carbon free material comprising iron 16.9%, silicon 1.7%, a metal selected from the group comprising chromium, tungsten, vanadium, and molybdenum 2.2% and the balance nickel. In testimony that we claim the foregoing as our invention we have signed our names this fifth day of January, 1927.

WILLOUGHBY STATHAM SMITH. HENRY JOSEPH GARNETT.

JOHN ANCEL HOLDEN. 

